The present invention relates generally to semiconductor fabrication and more specifically to methods of forming dual-damascene structures.
The current plug filling processes for dual-damascene processes have fencing issues or involve additional process steps and increased processing costs to alleviate the fencing issues.
U.S. Pat. No. 6,268,283 B1 to Huang describes a dual-damascene process using a resist cap in the dual-damascene opening.
U.S. Pat. No. 6,057,239 to Wang et al. describes a dual-damascene process using a sacrificial plug.
U.S. Pat. No. 6,033,977 to Gutsche et al. describes another dual-damascene process also using a sacrificial plug.
U.S. Pat. No. 6,096,655 to Lee et al., U.S. Pat. No. 5,635,423 to Huang et al. and U.S. Pat. No. 5,920,790 to Wetzel describe related dual-damascene processes.
Accordingly, it is an object of one or more embodiments of the present invention to provide an improved method of forming a dual-damascene structure.
Other objects will appear hereinafter.
It has now been discovered that the above and other objects of the present invention may be accomplished in the following manner. Specifically, a structure having a patterned low-k material layer formed thereover is provided. The patterned low-k material layer having an upper surface and at least one via hole formed therethrough. A plug material layer is formed over the patterned low-k material layer and filling the at least one via hole. The plug material layer being comprised of a material dissolvable in TMAH or deionized water. The plug material layer is developed to form a plug within the respective at least one via hole having a height below the upper surface of the patterned low-k material layer. The plug is baked to crosslink the plug material comprising the plug. A trench masking layer is formed and patterned to form a patterned trench masking layer having at least one trench substantially centered over the respective at least one via hole and exposing a portion of patterned low-k material layer adjacent the at least one via hole. Wherein the crosslinked plug material comprising the plug does not adversely interact with the trench masking layer. The patterned low-k material layer is etched at the exposed portion using the patterned trench masking layer as a mask to form a trench opening substantially centered over the via hole. The etching of the patterned low-k material layer also removing some of the plug to form a partially etched plug. The trench opening and the via hole comprising a dual-damascene opening. The partially etched plug is removed from the via hole. A planarized dual-damascene structure is formed within the dual-damascene opening.